Visual inspection of turbine blades

ABSTRACT

A blade monitoring system is provided for inspecting the condition of at least one turbine blade of a wind turbine generator. The wind turbine blade condition monitoring system includes a wind turbine which has at least one blade mounted on a hub, the hub mounted to a nacelle body along an axis of rotation, the nacelle being supported on a tower. A storage location is connected to at least one of the nacelle body and the tower and includes an opening. A storage door is mounted to and selectively covers the opening, acting to enclose the storage location. The blade monitoring system also includes imaging equipment for imaging the at least one blade and a conveyance system. The conveyance system is mounted to at least one of the nacelle body and the tower and is connected to the imaging equipment. The conveyance system conveys the imaging equipment from within the storage location through the opening in a direction generally parallel to a longitudinal axis of the at least one blade.

BACKGROUND

The present exemplary embodiment relates to wind turbines. More particularly, it relates to a monitoring system for inspecting the condition of wind turbine rotor blades.

The increasingly complex and optimized blade designs of wind turbine generators, along with the increase in physical scale and sheer volume of off-shore wind turbines, have made the need for blade condition monitoring more critical to ensure early warning of potential design, manufacture, assembly or operation induced damage to the blades.

A variety of camera systems for monitoring the condition of wind turbine components are known. The current state of the art for inspecting turbine blades in fully assembled wind turbine generators includes periodic human inspection of the blades through cameras statically mounted to the wind turbine. Also known is the use of a camera mounted to a lifting device positioned on a vehicle driven up to the tower on which the blades are to be inspected. These methods are subject to a number of limitations. There are environmental restrictions on when such inspections can occur, as well as inaccuracies due to the subjectiveness of the inspection. In addition, there is the physical distance from which the inspection takes place. Inspecting wind turbines mounted in a water environment is particularly problematic due to the relative inaccessibility of such turbines, as well as humidity and corrosion issues. With regard to statically mounted cameras, a limitation is the narrow area of the blade that can be imaged by the camera.

It would be advantageous to provide for automated inspection of wind turbine blades in a wider range of environmental conditions with the ability to inspect the entire blade from root to tip at a closer distance. It would also be desirable to improve the objectiveness of the inspection through processing and analyzing algorithms.

BRIEF DESCRIPTION

According to one embodiment of the present disclosure, a wind turbine blade condition monitoring system is provided. In accordance with this embodiment of the disclosure, the wind turbine blade condition monitoring system comprises a wind turbine including at least one blade mounted on a hub, the hub mounted to a nacelle body along an axis of rotation, the nacelle body being supported on a tower. A storage location is connected to or defined in at least one of the nacelle body and the tower. The storage location includes an opening, and a storage door mounted to and selectively covering the opening, and acting to enclose the storage location. The system also includes imaging equipment for imaging the at least one blade and a conveyance system mounted to at least one of the nacelle and the tower and connected to the imaging equipment. The conveyance system conveys the imaging equipment from within the storage location through the opening in a direction generally parallel to a longitudinal axis of the at least one blade.

In accordance with another embodiment of the present disclosure, a wind turbine blade monitoring system is provided. The wind turbine blade condition monitoring system comprises imaging equipment for imaging at least one portion of a blade of an associated wind turbine and a conveyance system mounted to at least one of a nacelle and a tower of the associated wind turbine. The conveyance system comprises a first pulley mounted to the at least one of the nacelle and the tower of the associated wind turbine, a first motor for selectively rotating the first pulley, and a first support cable mounted to the first pulley. The first support cable includes a load end connected to the enclosure and a winding end mounted on the first pulley. The conveyance system moves the imaging equipment in a direction generally parallel to a longitudinal axis of the blade of the associated wind turbine from adjacent a root end of the blade to a tip end thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure may take form in various components and arrangements of components as will be pointed out more fully hereinafter in conjunction with the written description of the preferred embodiments and illustrated in the accompanying drawings in which:

FIG. 1 is a schematic view of a wind turbine and a wind turbine blade condition monitoring system according to one embodiment of the present disclosure;

FIG. 1A is a schematic view of an alternative embodiment of a wind turbine blade condition monitoring system according to the present disclosure, where the conveyance system attaches to the enclosure at multiple attachment points;

FIG. 2A is a schematic view of another alternative embodiment of a wind turbine blade condition monitoring system according to the present disclosure, where the conveyance system comprises an electromechanical pulley and track system;

FIG. 2B is a schematic view of still another alternative embodiment of a wind turbine blade condition monitoring system according to the present disclosure;

FIG. 2C is a schematic view of yet another alternative embodiment of a wind turbine blade condition monitoring system according to the present disclosure;

FIG. 3 is an enlarged exploded schematic view of an enclosure and imaging equipment of the monitoring system of FIG. 1;

FIG. 4 is a schematic view of a further alternative embodiment of a wind turbine blade condition monitoring system according to the present disclosure;

FIG. 4A is an enlarged schematic top plan view of a portion of the monitoring system of FIG. 4;

FIG. 5 is an enlarged schematic side view of a nacelle storage door of the monitoring system of FIG. 1 sealingly engaged to the nacelle body;

FIG. 6 is a schematic view of a wind turbine blade condition monitoring system according to a yet further embodiment of the present disclosure;

FIG. 7 is a schematic view of a further alternative embodiment of a wind turbine blade condition monitoring system according to the present disclosure; and,

FIG. 8 is a schematic view of still a further embodiment of the present disclosure.

DETAILED DESCRIPTION

Referring now in greater detail to the drawings wherein the showings are for purposes of illustrating several embodiments of the disclosure only and not for limiting same. FIG. 1 depicts one embodiment of a turbine blade monitoring system. In this embodiment, the wind turbine blade condition monitoring system utilizes an electromechanical pulley system for selectively moving imaging equipment along the length of a turbine blade employed in a wind turbine. The wind turbine is mounted on a tower 10 and comprises at least one turbine blade 22 mounted to a hub 20, where the hub 20 is attached to a nacelle 30 along an axis of rotation 24, and the nacelle 30 is mounted atop the tower 10. A storage area 32 is defined in the nacelle. In this embodiment, the storage area is accessible from the bottom face of the nacelle. Of course, other geometries are also contemplated. A storage door 64 is movably mounted to the nacelle 30 and selectively covers a nacelle opening 62. The door 64 acts to enclose the storage area 32.

A conveyance system, mounted to the nacelle body 30, is connected to and conveys an enclosure 40 from within the storage location 32 through the opening 62 and in a direction generally parallel to a longitudinal axis of the at least one blade 22. In this embodiment, the enclosure 40 holds imaging equipment for imaging the at least one blade 22. The conveyance system can include an electromechanical pulley system, comprising a first pulley 66 mounted to the nacelle body 30, and a first support cable 44 mounted on the first pulley 66. The first support cable 44 includes a load end and a winding end, where the winding end is driven by a conventional motor unit (not visible) that rotates the pulley and the load end is attached to the enclosure 40. A power/data cable 42 is connected to imaging equipment held in the enclosure, as is illustrated in FIG. 3. The data component of cable 42 communicates with an electronic cable 118 disposed in the nacelle 30 and connected to a data receiving system 120. The data receiving system 120 contains processing and analyzing algorithms to analyze data transmitted by the imaging equipment.

It should be appreciated that the data receiving system 120 could be located remotely from the nacelle 30, if so desired. Communication can be had with such a remotely located data receiving system via RF, for example. In such an embodiment, a conventional RF transmitter (see FIG. 7) could be located in the housing 40 and the cable 42 would only be a power cable to provide electricity to the imaging system and to the RF transmitter held in the housing.

With reference to FIG. 1A, another embodiment of the conveyance system of a wind turbine blade condition monitoring system 2 is there shown. In this embodiment, like components are identified by like numerals with a primed (') suffix, and new components are identified by new numerals. The wind turbine comprises at least one turbine blade 22′ mounted to a hub 20′, where the hub 20′ is attached to a nacelle 30′, and the nacelle 30′ is attached to a tower 10′. A storage location 32′ having an opening 62′ is located in the nacelle 30′. A storage door 64′ is mounted to and selectively covers the opening 62′ and acts to selectively enclose the storage area or location 32′. A conveyance system, which can be mounted to the nacelle body 30′, is connected to and conveys an enclosure 40′ from within the storage location 32′ through the opening 62′ and in a direction generally parallel to a longitudinal axis of the at least one blade 22′. The enclosure 40′ holds imaging equipment for imaging the at least one blade 22″.

In this embodiment, the conveyance system comprises first and second pulleys 84, 80 mounted to the nacelle body 30′. A first support cable 88 is mounted on the first pulley 84, and a second support cable 82 is mounted on the second pulley 80, Each of the support cables 82, 88 includes a load end and a winding end. The load end of the second support cable 82 is attached to the enclosure 40′ at a location spaced from where the first support cable 88 is attached to the enclosure 40*. Employing two or more spaced cables is advantageous in order to reduce the tendency of the housing 40′ to swing or pivot, for example due to wind, as the housing is moved up and down generally along a longitudinal axis of the blade 22′. The inspection of the rotor blade is facilitated when the blade to be inspected is placed in the 6 o'clock position, i.e., the rotor blade is extending generally straight down from the hub and is therefore aligned with the tower.

With reference now to FIG. 2A, another embodiment of the conveyance system of a wind turbine blade condition monitoring system is there shown. The wind turbine comprises at least one turbine blade 122 mounted to a hub 120, where the hub 120 is attached to a nacelle 130 along an axis of rotation 124, and the nacelle 130 is attached to a tower 110. A storage area or location 132 and an opening 162 is located in a body of the nacelle 130. A storage door 164, mounted to and selectively covering the opening 162, acts to enclose the storage location 132. A conveyance system, mounted to the nacelle body 130, is connected to and conveys an enclosure 140 from within the storage location 132 through the opening 162 and in a direction generally parallel to a longitudinal axis of the at least one blade 122. The enclosure 140 holds imaging equipment for imaging the at least one blade 122.

In this embodiment, the conveyance system comprises an electromechanical pulley and track system including at least one pulley 194 and at least one roller 195 mounted to the nacelle body 130, and a support cable 196 supported by the pulleys and rollers. A data and power cable 198 is also provided. The support cable 196 includes a load end and a winding end, where the winding end is driven by a motor unit (not visible) that rotates the at least one pulley 194. The load end is attached to a carriage 192. The enclosure 140′ is attached to the carriage 192 which travels along a track 190 that is attached to the tower. The carriage 192 is supported on the track 190 and is raised and lowered by the support cable 196. The track 190 in this embodiment is supported by and hangs from the nacelle 130. The track 190 also rides against the tower 110. To this end, a series of spaced rollers 184 are attached to the track 190. When the nacelle 130 rotates (i.e., yaws) relative to the tower 110, the rollers allow the track to ride against the tower and rotate with the nacelle. It should be appreciated that the track 190 can extend down the tower 110 the length of the blade 122 in order to enable the carriage 192 to transport the housing 140 from a location adjacent a root end of the blade to a location adjacent a tip end thereof. In order to allow the housing 140 to be retracted into the nacelle 130 for storage, an upper end of the track 190 can extend into the storage area 132. Of course, other embodiments are also contemplated. It should be appreciated that the storage door 164 will need to be modified in order to accommodate the track 190.

With reference now to FIG. 2B, another embodiment of the present disclosure is there illustrated. In this embodiment, like components are identified by like numerals with a primed suffix (') and new components are identified by new numerals. In this embodiment, a track 200 is hard mounted to a tower 110′ and does not rotate with a nacelle 202. Rather, the track, relevant pulleys 194′ and related components are all mounted to the tower 110′ and do not rotate with the nacelle 202. However, the nacelle still helps form an enclosure around the carriage when it is not in use. In this embodiment, the nacelle 202 extends well below a slew bearing 204 which connects the tower to the nacelle to form an area where the nacelle can still wrap around and protect equipment which is mounted to the tower beneath the slew bearing. A portion 206 of the nacelle 204 is hard mounted to the tower 110′. That nacelle portion 206 is joined to the remainder of the nacelle 202 at a circular intersection and forms a rotary joint 208, which can be designed with baffles or serpentine seals in order to keep weather out of the nacelle. In one embodiment, the nacelle 202 and the nacelle portion 206 can be made of a fiberglass material. In this embodiment, a fixed barrier 209 is provided which is mounted below the carriage 140′ to protect the carriage in the nacelle 202 until the carriage leaves the enclosed space so as to undertake an inspection. Such inspection will require that the blade 122′ be in a specific angular orientation in relation to the carriage 140′.

In the embodiments thus far illustrated herein, the imaging equipment and its housing have been stored within a cavity defined in the nacelle. However, it should be appreciated that a separate housing member, configured for storing the imaging equipment, could be affixed to a wall of the nacelle instead. In other words, it may be desirable in some circumstances to provide a separate housing member which is mounted to either the nacelle or the tower, which housing or enclosure is meant to accommodate the imaging equipment when such equipment is not needed for inspection of a turbine blade of the wind turbine. One such embodiment is shown in FIG. 2C.

With reference now to FIG. 2C, another embodiment of an inspection system is there illustrated. In this embodiment, like components are identified by like numerals with a double primed suffix (″) and new components are identified by new numerals. In this embodiment, a carriage 211 is not pulled up and let down by a cable. Rather, the carriage 211 is self propelled. In one embodiment, the carriage 211 could be provided with gears so that the carriage runs on a geared track 190″ in order to prevent slippage or skidding due to gravity. In other words, a rack and pinion type arrangement vertically oriented could be employed. Of course, other known alternatives could be utilized as well. Imaging equipment in the carriage can receive power from a power and data cable 213. The carriage has an electric motor (not illustrated) or other means so that the carriage can climb and lower itself on the track 190″. In this embodiment, the track is hard mounted to a tower 110″. However, the track does not extend up to a nacelle 130″. Rather, the carriage has a separate enclosure 215 mounted to the tower for storing the carriage when it is not in use. A suitable door 217 can be employed to close an opening in the enclosure 215 when the carriage is put away for storage. It should be appreciated that the door 217 is formed to accommodate the protrusion of the track upper end into the enclosure 215.

With reference now to FIG. 3, the enclosure 40 which can hold the imaging equipment 52, 54 is there shown. The enclosure comprises a housing unit including a camera mount 48 defining a hollow chamber 46. Attached thereto is a transparent viewing window 50. The imaging equipment can comprise a camera 52 which includes a lens 54. In one embodiment, the imaging equipment can employ visible light to image the blade. Other types of imaging equipment are also contemplated. For example, X-ray imaging technologies or other known means of inspection could be used to inspect the blades. The lens 54 of the imaging equipment faces the transparent viewing window 50 for imaging the at least one turbine blade.

With reference now to FIG. 5, one embodiment of a nacelle door 104 is shown along with sealing surfaces with a nacelle body 100 in order to prevent exposure of the imaging equipment and its enclosure to the elements. More particularly, sealing surfaces 106 are defined on at least one of the storage door 104 and the nacelle body 100 for sealingly engaging the storage door with the nacelle body. Due to the high humidity and saline environment found in offshore wind turbine installations, the vast majority of which are in salt water, it is very desirable to provide adequate sealing for the nacelle so that the equipment held or stored therein is not subjected to the environment. It is also advantageous to store the imaging equipment in the nacelle when not needed, to keep it away from such a marine environment. Even where the movable imaging equipment disclosed herein is used on a wind turbine mounted on shore, it is advantageous to store the imaging equipment in an enclosed storage area, such as within the nacelle, when not needed in order to retard dirt and dust from clogging the equipment.

With reference now to FIG. 4, another embodiment of a wind turbine blade condition monitoring system 4 is there shown. In this embodiment, the wind turbine comprises at least one turbine blade 222 mounted to a hub 220, where the hub is attached to a nacelle 230, and the nacelle is attached to a tower 210. A storage area or location 232 and an opening 262 is located in the nacelle body 230. In this embodiment, a rearwardly pivoting storage door 220 is mounted to the nacelle and selectively covers the nacelle opening 262 in order to enclose the nacelle storage location 232. A conveyance system, mounted to the nacelle body 230 is connected to and conveys an enclosure from a storage position through the nacelle opening 262 to an imaging position. As in the previous embodiments, the enclosure holds imaging equipment for imaging the at least one blade 222. The conveyance system comprises an electromechanical pulley system, including a first pulley 226 mounted to the nacelle body 230, and a first support cable 228 mounted on the first pulley. The first support cable 228 rides on a set of rollers or second pulleys 229. The cable includes a load end and a winding end, where the winding end mounted on the pulley 226. As shown in FIG. 4A, the pulley 226 is driven by a motor unit 232 that rotates the pulley and the load end is attached to the enclosure.

With reference now to FIG. 6, illustrated therein is a different position for the storage location according to the present disclosure. In this embodiment, a storage location 350 is provided outside a nacelle 352. For example, the storage location 350 can be a separate enclosure which is mounted to the nacelle 350. Alternatively, the storage location could be mounted to a tower 354 (see FIG. 2C). The storage location includes a storage area 356 which accommodates a conveyance system 360, as well as an enclosure 362 which can hold holding imaging equipment for imaging the at least one blade. While the imaging equipment is generally shown as being held in a housing, it should be appreciated that such a housing is not necessary under all circumstances. In other words, the imaging equipment could itself be held in a storage location without the need for a housing to enclose the imaging equipment.

With reference now to FIG. 7, disclosed is a further embodiment in which the imaging system is mounted to a personnel lifting basket 470. In this embodiment, the wind turbine comprises at least one turbine blade 422 mounted to a hub 420 which rotates around an axis 424. The hub is attached to a nacelle 430, and the nacelle is mounted on a tower 410. An access area or location 474 and an opening 478 is located in the nacelle body 430. An access door 472 is mounted to and selectively covers the opening 478 and acts to selectively enclose the access area or location 474. A conveyance system, mounted to the nacelle body 430 is connected to and conveys a personnel lifting basket 470 to and from a position near the access area or location 474 in a direction generally parallel to a longitudinal axis of the at least one blade 422. It is appreciated that personnel are transported in the basket from a base of the tower 410 to the nacelle 430. Access to the nacelle can be provided by the illustrated ladders. In this embodiment, when the basket 470 is not in use, it is drawn up against a bottom surface of the nacelle 430. To this end, the door 472 is closed before the basket is fully drawn up against the nacelle so that somewhat of a sealing relationship can be formed between the top edge of the basket 470 and the outer surface of the door 472. It should be appreciated that the door 472 is formed in such a way as to accommodate support cables 486 for the basket.

The enclosure 440 is affixed to the personnel lifting basket 470 and holds imaging equipment for imaging the at least one blade 422. As the basket 470 is raised and lowered, the at least one blade 422 can be imaged. The conveyance system can include an electromechanical pulley system, comprising first and second pulleys 482 mounted to the nacelle body 430, and first and second support cables 486 mounted on the first pulley and second pulley respectively. The first and second support cables 486 each include a load end and a winding end, where the winding end is spooled on a respective pulley which is driven by a conventional motor unit (not visible) that rotates the pulley. The load end of each cable is attached to the personnel lifting basket 470. Of course, more than two cables can be employed, if so desired. Three or four cables may be preferable.

In an alternative embodiment, the information transmitted by the imaging system is sent to a radio frequency transmitter 490 which can also be mounted in or to the basket 470. The transmitter 490 can transmit the information from the sensing system to a remote location. Similarly, there could be a transmitter within the nacelle 430 to transmit the information gathered by the imaging system to a remote location. This may prove particularly advantageous in an off shore wind farm setting.

With reference now to FIG. 8, disclosed is a further embodiment in which the imaging system is mounted to a personnel lifting basket 570. In this embodiment, the wind turbine comprises at least one turbine blade 522 mounted to a hub 520 that rotates around an axis 524. The hub is attached to a nacelle 530, and the nacelle is mounted on a tower 510. A storage area or location 532 and an opening 562 is located in the nacelle body 530. A storage door 564 is mounted to and selectively covers the opening 562 and acts to selectively enclose the storage area or location 532. In this embodiment, the nacelle 530 is enlarged in order to house the basket 570.

A conveyance system, mounted to the nacelle body 530 is connected to and conveys a personnel lifting basket 570 from within the storage location 532 through the opening 562 and in a direction generally parallel to a longitudinal axis of the at least one blade 522. The enclosure 540 is affixed to the personnel lifting basket 570 and holds imaging equipment for imaging the at least one blade 522. The conveyance system can include an electromechanical pulley system, comprising first and second pulleys 582 mounted to the nacelle body 530, and first and second support cables 586 mounted on the first pulley and second pulley respectively. The first and second support cables 586 each include a load end and a winding end, where each winding end is spooled on a respective pulley 582 which is driven by a conventional motor unit (not visible) that rotates the pulley. The load end of each cable is attached to the personnel lifting basket 570.

While the imaging system is illustrated in FIGS. 7 and 8 as being located at the base of the personnel basket 470, 570, it should be appreciated that the imaging system could be mounted to the personnel basket at a variety of locations. What is desirable is that the imaging system have a clear and unobstructed view of the at least one blade of the wind turbine.

The exemplary embodiments have been described herein. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiments be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof. 

1. A wind turbine blade condition monitoring system comprising: a wind turbine including: at least one blade mounted on a hub, the hub mounted to a nacelle along an axis of rotation, the nacelle being supported on a tower; a storage location connected to or defined in at least one of the nacelle and the tower and including an opening; a storage door mounted to and selectively covering the opening, acting to enclose the storage location; imaging equipment for imaging the at least one blade; and, a conveyance system mounted to at least one of the nacelle and the tower and connected to the imaging equipment, the conveyance system conveying the imaging equipment from within the storage location through the opening and in a direction generally parallel to a longitudinal axis of the at least one blade.
 2. The wind turbine blade condition monitoring system according to claim 1, wherein the conveyance system comprises an electromechanical pulley system, comprising: a first pulley mounted to the at least one of the nacelle and the tower; a first support cable mounted on the first pulley; the first support cable including a load end and a winding end, the winding end driven by a motor unit that rotates the pulley; and, wherein the load end is attached to the imaging equipment.
 3. The wind turbine blade condition monitoring system according to claim 2, wherein the conveyance system further comprises: a second pulley mounted to the at least one of the nacelle and the tower; a second support cable mounted on the second pulley; the second support cable including a load end and a winding end; the load end attached to the enclosure at a location spaced from the first support cable point of attachment.
 4. The wind turbine blade condition monitoring system according to claim 1, wherein the conveyance system comprises an electromechanical pulley and track system, comprising: a track mounted to the tower; a carriage which travels along the track; a system of pulleys mounted to the nacelle; a support cable supported by the system of pulleys; the support cable including a load end and a winding end, the winding end driven by a motor unit that rotates at least one of the system of pulleys; the load end attached to the carriage; and, wherein the enclosure is attached to the carriage.
 5. The wind turbine blade condition monitoring system according to claim 1, wherein the conveyance system further comprises a personnel lifting basket, including; at least one pulley mounted inside the nacelle; a support cable supported by the at least one pulley; the support cable including a load end and a winding end, the winding end driven by a motor unit that rotates the at least one pulley; the load end attached to a basket; and wherein the imaging equipment is attached to the basket.
 6. The wind turbine blade condition monitoring system according to claim 1, further including sealing surfaces defined on at least one of the storage door and the storage location for sealingly engaging the storage door with the storage location.
 7. The wind turbine blade condition monitoring system according to claim 1, further comprising a data receiving system containing processing and analyzing algorithms to analyze data transmitted by the imaging equipment.
 8. The wind turbine blade condition monitoring system according to claim 1, wherein the imaging equipment includes a camera and a lens.
 9. The wind turbine blade condition monitoring system according to claim 8, further comprising a housing unit defining a hollow chamber holding the imaging equipment and a transparent viewing window, wherein the lens of the imaging equipment faces the transparent viewing window.
 10. A wind turbine blade condition monitoring system, comprising: imaging equipment for imaging at least one portion of a blade of an associated wind turbine; a conveyance system mounted to at least one of a nacelle and a tower of the associated wind turbine, the conveyance system comprising: a first pulley mounted to the at least one of the nacelle and the tower of the associated wind turbine; a first motor for selectively rotating the first pulley; a first support cable mounted to the first pulley, the first support cable including a load end connected to the imaging equipment and a winding end mounted on the first pulley; wherein the conveyance system moves the imaging equipment in a direction generally parallel to a longitudinal axis of the blade of the associated wind turbine from adjacent a root end of the blade to a tip end thereof.
 11. The wind turbine blade condition monitoring system according to claim 10, wherein the conveyance system further comprises: a second pulley mounted to the at least one of the nacelle and the tower of the associated wind turbine; a second support cable mounted to the second pulley, the second support cable including a winding end mounted on the second pulley and a load end connected to the imaging equipment at a point spaced apart from the first support cable point of connection.
 12. The wind turbine blade condition monitoring system according to claim 11, wherein the conveyance system further comprises a second motor for selectively rotating the second pulley.
 13. The wind turbine blade condition monitoring system according to claim 10, wherein the conveyance system further comprises a data cable carrying data transmitted by the imaging system to a receiving system mounted to the nacelle of the associated wind turbine.
 14. The wind turbine blade condition monitoring system according to claim 10, further comprising a radio frequency transmitter for the remote transmission of data to one of the nacelle of the associated wind turbine and a remote location.
 15. The wind turbine blade condition monitoring system according to claim 10, wherein the imaging equipment includes a camera and lens.
 16. The wind turbine blade condition monitoring system according to claim 10, wherein the conveyance system further comprises a track mounted to a tower of the associated wind turbine.
 17. The wind turbine blade condition monitoring system according to claim 10, wherein the conveyance system further comprises a carriage running on the track, the enclosure being mounted to the carriage.
 18. The wind turbine blade condition monitoring system according to claim 10, further comprising a housing unit defining a hollow chamber accommodating the imaging equipment and a transparent viewing window, wherein the lens of the imaging equipment faces the transparent viewing window.
 19. The wind turbine blade condition monitoring system according to claim 10 wherein the enclosure is mounted to a personnel basket which is moved by the conveyance system. 